Electromagnetically operated switch



Patented July 25, 1939 UNITED STATES PATENT OFFICE ELECTROMAGNETICALLY OPERATED SWITCH Application July 7, 1937, Serial No. 152,407 In Germany November 2, 1935 4 Claims.

The invention relates to an electromagnetically operated switch whose switching elements, with the exception of the exciting coil, are enclosed in a container, for instance a glass container, which is evacuated or filled with an indifferent gas. The above mentioned exciting coil, as a rule, surrounds the container, hereinafter called vacuum container, which includes containers filled with an indifferent gas.

Although only a relatively small amount of power is required for operating such switches, the exciting coils, and the exciting energy, will be relatively large, because the coils necessarily must have a relatively large inner diameter and because the lines of force have to pass through the wall of the vacuum container in a relatively long air-gap. For this reason it has been proposed to reduce the operating energy of such switches by forming the wall of the vacuum container which is penetrated by the magnetic flux relatively thin. However, such vacuum containers, with metal portions melted into the glass wall, are liable to be damaged and are expensive to manufacture. Besides, they do not offer the advantage of perfect electric isolation between the inside and the outside of the vacuum container.

According to the invention, the pole-shoe as well as the armature is arranged inside the vacuum container. The armature and the pole-shoe with the greatest possible face are arranged closely adjacent the inner wall of the container, and there is a fully or partly closed ferromagnetic casing for the exciting coil, constructed in such a way that the greatest possible face lies adjacent the outer wall of the container opposite the armature and pole-shoe.

The various objects and features of the invention will be apparent to those skilled in the art upon a consideration of the accompanying drawing and the following description wherein several exemplary embodiments of the invention are disclosed.

In the drawing:

Fig. 1 is a longitudinal sectional view of the switch.

Fig. 2 is a similar view illustrating a modification of the magnetic circuit.

Fig. 3 is a cross sectional view of the apparatus shown in Fig. 2.

The vacuum switch itself consists of a fixed contact I and a movable contact 2. The fixed contact I is fitted into an insulating body 3 adjoining another insulating body 4, the latter being the guide for the movable contact 2. Fastened to the two insulating bodies 3 and 4 is the pole-shoe 5, or the not-movable ferromagnetic 1 portion of the vacuum switch. Opposite this pole-shoe 5 there is an armature 6 as the movable portion of the switch. This armature can slide along the periphery of the insulating body 3. The armature 6 is also guided by two guiding rods 1, by which the insulating bodies 3 and 4 are at the same time held together. The armature 6 is urged away from the pole-shoe 5 by a spring 8, while a plate 9, pressed into the armature, engages a pin H] in the movable contact 2, whereby the contacts are kept open against the pressure of the spring H. A plate 12, secured to the end of the guiding rods 1, serves to limit the movement of the armature 6. The plate 12 is provided with a few elastic attachments l3, serving to support the whole switching system against the wall of the vacuum container 14. The movable contact is electrically connected with the guiding rods 1 by means of an elastic current bridge l5. Two current conductors 16 are sealed at I! in the vacuum container and are connected at l8 and H) with the movable contact through the guiding rods 1 on the one hand, and on the other hand with the fixed contact.

In the drawing, the vacuum container is shown as a tubular body. The pole-shoe and armature are also formed tubular so that the faces of these two parts on a very long distance lie closely adjacent the glass wall. The vacuum container 14 is located within an electromagnetic coil 20. This electromagnetic coil is surrounded bya pot-shaped force-1ines-conducting-vessel 2|, consisting of a ferromagnetic material and extending far enough into the interior of the coil at 22 to closely join, on the greatest possible distance, the wall of the glass container I4, whereby a very large section of the magnetic flux is caused to pass through the glass container, for which reason relatively few ampere-turns are required to move the armature. Naturally, the ends 22 must not be so near to each other that between them a stray flux is caused, evading the armature and pole-shoe, which would weaken the action.

When current passes through the coil, a ma netic flux is caused to pass through the portions 2| from 22 at the top through the glass l4 and through the air-gap 23 to the pole shoe 5 and through the glass M to 22 at the bottom. Thereby the armature 6 is attracted by the pole-shoe 5, closing the contacts under the action of the spring H. When the current no longer passes through the coil the armature 6 is moved upwardly by means of the spring 8. The plate 9 then engages the pin It to move the contact 2 away from the fixed contact l. In order to make such a switch suitable for exciting by alternating current, it is necessary to at least let two alternating magnetic fluxes pass through the air-gap 23, independent of each other and being so out of phase that the attraction caused by the magnetic flux is never smaller than the counteracting power of spring 8. With electromagnetic switches in air the genera-= tion of two such magnetic fluxes is relatively simple by providing the divided pole-shoe with a short-circuit winding, more or less surrounding the pole-shoe. In the case of such vacuum switches, this is connected with relatively great difliculties and, owing to the relative smallness of the moved masses, and a short circuit coil does not always lead to the desired aim of preventing the armature and the contacts from vibrating and humming.

Two or more coils may be used which have two or more separate conductors of lines of force which generate in the pole shoe and armature two or more independent fluxes or lines of force and thereby prevent the vibration of the armature. A constructional example of this type is shown in Figures 2 and 3. 26 is the vacuum container in which there are two separate pole shoes 24, 35 and two separate armatures 25 and 36 belonging thereto. 21 and 38 indicate two coils which have a ferromagnetic core 28 or 3! and conducting pieces 29 and 32. These conducting pieces 29 and 32 are separate as shown in Fig. 3 and closely adjoin the major portion of the circumference of the glass container 26.

If a condenser 33 of corresponding capacity is connected in series with the coil 30 and if the coil 3% with the condenser 33 is then connected in parallel with the coil 2! and an alternating voltage is applied to the mutual conductors 34, there is produced under the influence of the condenser in the coil 3d a current which is out of phase with the current in the coil 21. The magnetic flux of the coil 2'! will extend to one half of the pole shoe and armature on the right side of Fig. 3 and the magnetic flux of the coil 38 will extend to the left side of these parts. The two magnetic fluxes produced in armature and pole shoe are also out of phase so that the attraction between armature and pole shoe can never be zero. The armature will always remain attracted in spite of the alternating voltage and will not vibrate.

It is also possible to construct the switch according to the invention so that the contacts open when the coils are excited.

What I claim is:

1. An electromagnetically operated switch comprising, an evacuated container, a fixed cylindrical pole-shoe arranged within the container with the entire length and entire circumference of the poleshoe closely adjacent the wall of the container, a movable cylindrical armature arranged with the entire length and in .its entire circumference closely adjacent the inner wall of the container, exciting windings outside the container, a conductor of lines of force arranged outside the container and extending over the approximate length of the armature and the pole-shoe and over a large part of the circumference of the glass container, a hollow insulating body secured to the pole-shoe and partly extending into the armature, a fixed contact secured in the insulating body, a movable contact, said insulating body having an opening therein through which the movable contact extends into the hollow space of the insulating body.

2. An electromagnetically operated switch com prising, an evacuated container, a fixed cylindrical hollow pole-shoe arranged within the container with the entire length and entire circumference of the pole-shoe closely adjacent the wall of the container, a movable cylindrical armature arranged with the entire length and in its entire circumference closely adjacent the inner wall of the container, exciting windings outside the container, a conductor of lines of force arranged outside the container and extending over the approximate length of the armature and the pole-shoe and over a large part of the circumference of the glass container, a hollow insulating body secured to the pole-shoe and extending partly into the armature and partly into the hollow pole-shoe, a fixed contact secured in the insulating body, a movable contact, said insulating body having an opening therein through which the movable contact extends into the hollow space of the insulating body, guide rods secured to the pole-shoe holding the insulating body, a plate in the interior of the movable armature and secured thereto, said plate having openings therein for guiding the plate and the armature on the guide rods, a plate secured to the ends of the guide rods, a pin carried by the movable armature, a helical spring arranged between the plate at the end of the guide rods and said pin, and a helical spring between the plate in the interior of the armature and the insulating body.

3. An electromagnetically operated switch comprising, an evacuated container, a fixed cylindrical hollow pole-shoe arranged within the container with the entire length and entire circumference of the pole-shoe closely adjacent the wall of the container, a movable cylindrical armature arranged with the entire length and in its entire circumference closely adjacent the inner Wall of the container, exciting windings outside the container, a conductor of lines of force arranged outside the container and extending over the approximate length of the armature and the pole-shoe and over i a large part of the circumference of the glass container, a hollow insulating body secured to the pole-shoe and extending partly into the armature and partly into the hollow pole-shoe, a fixed contact secured in the insulating body, a movable contact, said insulating body having an opening therein through which the movable contact extends into the hollow space of the insulating body, guide rods secured to the pole-shoe holding the insulating body, a plate in the interior of the movable armature and secured thereto, said plate having openings therein for guidin the plate and the armature on the guide rods, plate secured to the ends of the guide rods, a pin carried by the movable armature, a helical spring arranged between the p late at the end of the guide rods and said pin, a helical spring between the plate in the interior of the armature and the insulating body, and resilient attachments on the plate at the ends of the guide rods bearing against the inner wall of the container.

4. An electroma gnetically operated switch comprising, an evacuated container, a fixed cylindrical hollow pole-shoe arranged within the container with the entire length and entire circumference of the pole-shoe closely adjacent the wall of the container, a movable cylindrical armature arranged with the entire length and in its entire circumference closely adjacent the inner wall of the container, exciting windings outside the container, a

conductor of lines of force arranged outside the a large part of the circumference of the glass container, a hollow insulating body secured to the pole-shoe and extending partly into the armature and partly into the hollow pole-shoe, a fixed contact secured in the insulating body, a movable contact, said insulating body having an opening therein through which the movable contact extends into the hollow space of the insulating body, guide rods secured to the pole-shoe holding the insulating body, a plate in the interior of the movable armature and secured thereto, said plate having openings therein for guiding the plate and the armature on the guide rods, a plate secured to the ends of the guide rods, a pin carried by the movable armature, a helical spring arranged between the plate at the end of the guide rods and said pin, a helical spring between the plate in the interior of the armature and the insulating body, current conductors extending into the interior of the hollow pole-shoe electrically connected to the fixed contact and to one of the guide rods, and an electrically conducting resilient connection between the movable contact and the last mentioned guide 10 rod.

ERNST ROZUMEK. 

